In forming materials such as pipe insulation from liquids which transform themselves to a solid, undergoing a transitory foam state, it has been found that the material within the foam state places forces on the mold, in some instances displacing the mold from a set position.
This movement within the mold causes distortion in the product. In the case of pipe insulation, an inner mold is mounted within the outer mold and the liquid is inserted therebetween. During the foaming process, forces exerted on the inner mold may displace the inner mold from its centered position causing a distortion in the concentricity between the inner wall of the finished pipe and the outer wall.
A machine for making pipe insulation from an injected liquid and upon which this invention may be practiced is shown in U.S. Pat. No. 3,985,483.